Multiple standards exist for sizing wearable items, such as eyeglasses and jewelry. Various manufacturers and designers size their items according to any one of these standards, and occasionally develop new standards. It follows that a large shirt from one brand may be bigger than a large shirt from a different brand. Likewise, one brand's size 10 running shoe may fit differently than another brand's size 10 running shoe. In addition, some wearable items, such as rings and hats, are not sold in broad size categories, such as small, medium, and large. Instead, these items require precise measurements from a user to fit properly.
When the size of an item is needed, a user typically has to guess the proper size to select, particularly if the user is unfamiliar with the brand or manufacturer of the items. Because some speculation is involved, it can be difficult for a user to select the proper size on the first try. Unfortunately, this mistake often is not revealed until a user attempts to wear or use an item. If the user guessed incorrectly, as is often the case, the user must make a new selection based on how the “wrong” selection fit.